Disclosure of Invention
The invention aims to provide an ampere force-based flexible catheter and a control method thereof, which are used for controlling the posture of the flexible catheter.
1. Flexible conduit based on ampere force
The flexible conduit comprises an electrified conducting wire, a magnetic shielding material and an outer hose; an opening at one end of the outer hose serves as an open end, the other end of the outer hose is closed and serves as a closed end, the electrifying conducting wire is arranged in a folded mode and divided into two sections, one or more parts of one section of the electrifying conducting wire are coated with magnetic shielding materials, the other section of the electrifying conducting wire is not coated with the magnetic shielding materials, the folded part in the middle is arranged in the closed end of the outer hose, and the two ends of the electrifying conducting wire extend out of the open end of the outer hose and then are respectively and electrically connected with two electrodes of an external power supply to form a loop.
In a magnetic field, the ampere force borne by one section of the electrified conducting wire wrapped with the magnetic shielding material is unequal to the ampere force borne by the other section of the electrified conducting wire not wrapped with the magnetic shielding material, so that the resultant force borne by the electrified conducting wire is not zero, namely the stress difference between the electrified conducting wires on two sides is not zero, the flexible conduit is deformed by external force and deflects for a certain angle, the middle folded part is arranged in the closed end of the outer-layer hose, and the two ends of the electrified conducting wire extend out of the open end of the outer-layer hose and then are respectively and electrically connected with two electrodes of a power supply to form a loop.
The method specifically comprises the following steps: the opening of outer hose one end is as the open end, the outer hose other end seals as the blind end, the one end of circular telegram wire is connected with an electrode electricity of power, the other end of circular telegram wire leads to outer hose blind end from outer hose open end, then through reverse buckling extend back from outer hose blind end to outer hose open end and be connected with another electrode electricity of power, and form the return circuit, from outer hose open end to one on the circular telegram wire of outer hose blind end cladding magnetic screen material, and on the circular telegram wire that leads to outer hose open end from outer hose blind end not cladding magnetic screen material, or lead to outer hose open end from outer hose blind end cladding magnetic screen material, and on the circular telegram wire that leads to outer hose closed end from outer hose open end not cladding magnetic screen material, in magnetic field, the circular telegram wire that cladding magnetic screen material receives ampere force that circular telegram wire and the circular telegram wire that does not clad magnetic screen material received, make circular telegram wire receive the resultant force that the circular telegram wire received, the circular telegram both sides wire atress difference is not zero, and then make the flexible conduit receive external force, take place deformation, deflect certain angle. The method is characterized in that an electrified lead in a magnetic field can be acted by ampere force, the magnitude of the ampere force is in direct proportion to the magnetic induction intensity of the magnetic field, the magnitude of electrified current and the length of the lead, the force direction of the ampere force is related to the current direction and the magnetic field direction, and the ampere force can be obtained by left-hand rule; the other electrified lead at the corresponding position is not wrapped by any substance, and the two leads are not stressed equally, so that the flexible conduit is subjected to external force.
The outer layer hose is made of flexible materials.
The magnetic shielding material is made of ferrite magnetic material.
The electrified lead is made of copper material or aluminum material.
2. Control method of flexible catheter based on ampere force
The method comprises the following steps:
s1: the method comprises the following steps that a flexible guide pipe, an external camera, a magnetic field generating device, a controller and a power supply form a control system, the camera is connected with the controller in the process of controlling the flexible guide pipe, and the power supply is respectively connected with the opening end of the flexible guide pipe, the controller and the magnetic field generating device;
s2: the method comprises the following steps that information of the position of a flexible conduit and an advancing line is obtained by a camera in a control system and is sent to a controller, and the controller obtains an expected deflection angle theta of the flexible conduit according to the obtained information;
s3: the corresponding relation between the expected deflection angle theta of the flexible conduit and the magnetic induction intensity of the magnetic field generating device and the current of the electrified lead is obtained by adopting the following formula: when the magnetic induction intensity of the magnetic field generating device conforming to the flexible conduit is calculated, the current of the electrified conducting wire is controlled to be unchanged; when the current of the electrified lead conforming to the expected deflection angle theta of the flexible conduit is calculated, controlling the magnetic induction intensity of the magnetic field generating device to be unchanged;
wherein E represents the elastic modulus of the flexible conduit; i is 0 Indicating flexible conduitsArea moment of inertia of the shaft cross section; b represents magnetic induction intensity; d represents the length of the energized conductor; i represents the current of the electrified wire; l represents the length of the flexible conduit; ε represents a constant relating to the effect of magnetic shielding; r represents the vector between the open end of the outer hose to the magnetic shield material; in a specific implementation, there may be a plurality of magnetic shielding materials coated on the current conducting wire leading from the open end of the outer hose to the closed end of the outer hose or a plurality of magnetic shielding materials coated on the current conducting wire leading from the closed end of the outer hose to the open end of the outer hose, where r in the formula is the sum of vectors of the magnetic shielding materials to the open end of the flexible conduit.
S4: according to the corresponding relation between the expected deflection angle theta of the flexible conduit and the magnetic induction intensity of the magnetic field generating device and the current of the electrified lead, the controller processes and obtains the magnetic induction intensity of the magnetic field generating device or the current of the electrified lead, and sends an instruction to the power supply, the power supply applies corresponding magnetic induction intensity to the magnetic field generating device according to the obtained magnetic induction intensity instruction, at the moment, the current of the electrified lead is kept unchanged, or the power supply applies corresponding current to the flexible conduit according to the obtained current instruction of the electrified lead, at the moment, the magnetic induction intensity of the magnetic field generating device is kept unchanged;
then, under the action of a magnetic field or current, the ampere force borne by one section of the electrified lead wrapped with the magnetic shielding material in the outer-layer hose is unequal to the ampere force borne by the other section of the electrified lead not wrapped with the magnetic shielding material, so that the resultant force borne by the electrified lead in the outer-layer hose is not zero, namely the stress difference of the two sections of the electrified leads is not zero, the flexible guide pipe is further subjected to the external force, the flexible guide pipe deflects under the action of the external force, and the deflection angle is recorded as an actual deflection angle alpha to finish one deflection operation;
s5: after the flexible conduit finishes one deflection operation, the camera detects whether the actual deflection angle alpha of the flexible conduit is equal to the obtained expected deflection angle theta, and then the next step S6 is carried out;
s6: the following judgments were made: if the actual deflection angle alpha of the flexible conduit detected by the camera is equal to the expected deflection angle theta, the flexible conduit continues to move along the advancing line;
if the actual deflection angle alpha of the flexible conduit detected by the camera is not equal to the expected deflection angle theta, taking the absolute value of the difference value between the actual deflection angle alpha of the flexible conduit and the expected deflection angle theta as the expected deflection angle of the flexible conduit for the next deflection operation, and then repeating the steps S3-S5 until the actual deflection angle of the flexible conduit detected by the camera is equal to the expected deflection angle; the current value of the current lead of each deflection operation or the magnetic induction intensity value of the magnetic field generating device is increased or decreased by a corresponding value on the basis of the current value of the current lead of the previous deflection operation or the magnetic induction intensity value of the magnetic field generating device, and the current value of the current lead of the first deflection operation or the magnetic induction intensity value of the magnetic field generating device is the current value of the current lead or the magnetic induction intensity value of the magnetic field generating device which is calculated according to a calculation formula and conforms to the expected deflection angle theta of the flexible catheter in the step S2.
The invention realizes the posture control of the catheter by utilizing the ampere force applied to the electrified lead in the magnetic field and utilizes the magnetic shielding function of paramagnetic materials. The stress of the electrified lead in the magnetic field is in direct proportion to the magnetic induction intensity of the magnetic field, the current in the lead and the length of the lead, the stress direction can be obtained by the left hand according to the rule, namely, the five fingers of the left hand are straightened, the thumb and other four fingers are mutually vertical in the space, the magnetic induction line vertically passes through the palm of the hand, the directions of the four fingers are the same as the direction of the current, and the direction pointed by the thumb is the direction of the ampere force borne by the lead at the moment. The electric conducting wire is penetrated in the catheter, so that the ampere force of the conducting wire in the magnetic field can be utilized to control the posture change of the catheter. The electrified conducting wire leads to the tip from the tail end of the catheter and then returns from the tip to form a loop, the conducting wires in the two directions are equal in stress and opposite in direction, and the resultant force is zero. In order to obtain the force to the catheter, the magnetic shielding material such as ferrite is wrapped on part of one wire, the same position of the other wire is directly exposed in a magnetic field, the magnetic field in the region wrapped by the magnetic shielding material is reduced, the stress is reduced, the ampere force applied to the two wires is not equal any more, and the difference of the stress is the force to the whole catheter.
The flexible conduit manufactured by the technical scheme of the invention can change the deflection posture of the flexible conduit by changing the current of the lead in the conduit under the condition of not changing the external magnetic field. The catheter manufactured by the method not only can control the posture of the catheter by using the change of an external magnetic field, but also can control the posture of the catheter by adjusting the current in the lead under the condition that the external magnetic field is not changed.
The invention has the beneficial effects that:
the flexible conduit has good deflection performance, and the deflection angle of the flexible conduit can be changed by changing the current of the lead in the conduit under the condition that an external magnetic field is not changed so as to finish the control of the posture of the flexible conduit, or the deflection angle of the conduit is changed by changing the external magnetic field while keeping the electrified current of the lead in the flexible conduit unchanged; the deflection angle of the catheter can be changed by simultaneously changing the current of the lead in the catheter, and the flexible catheter can be combined with other catheters without the deflection angle.
Detailed Description
The invention is further illustrated with reference to the following figures and examples.
As shown in fig. 2, the flexible tube 4 of the present invention comprises an electric conduction wire 1, a magnetic shield material 2, and an outer layer hose 3; the electrified conducting wire 1 and the magnetic shielding material 2 are positioned in the outer layer hose 3, one or more parts of the electrified conducting wire 1 are coated with the magnetic shielding material 2, only one part is coated with the magnetic shielding material 2 in the specific implementation, and the purpose of realizing unbalance is achieved at any position. The outer hose 3 is made of flexible material; the magnetic shielding material 2 is made of ferrite magnetic material; the electrifying lead 1 is made of copper material or aluminum material.
The opening of 3 one ends of outer hose is as the open end, the closed as the blind end of 3 other ends of outer hose, 1 fifty percent discount of circular telegram wire is arranged and is divided into two sections, wherein the cladding has magnetic screen material 2 on one or more of one section circular telegram wire 1, another section leads to and does not wrap magnetic screen material 2 on electric lead 1, in the magnetic field, one section circular telegram wire 1 that has magnetic screen material 2 and another section that does not wrap magnetic screen material 2 lead to the ampere force inequality that electric lead 1 received, make circular telegram wire receive resultant force nonzero, the difference of 1 atress of both sides circular telegram wire is nonzero promptly, and then make flexible conduit receive external force, take place deformation, deflect certain angle, middle fifty percent discount is put in outer hose blind end, the both ends of circular telegram wire stretch out outer hose 3 open ends after respectively with the electric connection of two electrodes of power and form the return circuit.
In the specific implementation, an opening at one end of an outer hose 3 is used as an open end, the other end of the outer hose 3 is sealed and used as a closed end, one end of a power conducting wire 1 is electrically connected with one electrode of a power supply, the other end of the power conducting wire 1 leads to the closed end of the outer hose 3 from the open end of the outer hose 3, and then extends from the closed end of the outer hose 3 to the open end of the outer hose 3 through reverse bending and then is electrically connected with the other electrode of the power supply, and a loop is formed, one part of the power conducting wire 1 leading to the closed end of the outer hose 3 from the open end of the outer hose 3 is coated with a magnetic shielding material 2, and the power conducting wire 1 leading to the open end of the outer hose 3 from the closed end of the outer hose 3 is not coated with the magnetic shielding material 2, or the power conducting wire 1 leading to the open end of the outer hose 3 from the closed end of the outer hose 3 is coated with the magnetic shielding material 2, and the power conducting wire 1 not coated with the magnetic shielding material 2 is not coated with the magnetic shielding material 1 in a magnetic field, so that the resultant force applied to the power conducting wire 1 at two sides, i.e. the difference of the power conducting wire 1 is not zero, and further, the flexible conduit 4 deflects to an external force at a certain angle. The method is characterized in that an electrified lead 1 in a magnetic field can be acted by ampere force, the magnitude of the ampere force is in direct proportion to the magnetic induction intensity of the magnetic field, the magnitude of electrified current and the length of the lead, the stress direction of the ampere force is related to the current direction and the magnetic field direction and can be obtained by left-hand rule, in a lead loop in a flexible guide tube 4, the internal magnetic field borne by the electrified lead 1 wrapped with a small segment of magnetic shielding material 2 is weakened, and the ampere force borne by the external magnetic field borne by the electrified lead 1 wrapped with the small segment of magnetic shielding material 2 is negligible; the other electrified lead 1 at the corresponding position is not wrapped by any substance, and the two leads are not stressed equally, so that the flexible conduit 4 is subjected to external force.
The direction of the ampere force borne by the electrified lead in the magnetic field can be obtained by the left-hand rule, and the content is as follows: and (3) flatly stretching the left hand to ensure that the thumb is vertical to the other four fingers, the magnetic field points to the palm of the hand, the four fingers point to the current direction in the lead, and the direction pointed by the thumb is the direction of the ampere force applied to the electrified lead in the magnetic field. As shown in fig. 1, the magnetic field B is directed vertically into the paper, the current I in the wire 1 is directed upward, and the ampere force F to which the wire is subjected is directed horizontally to the left according to the left-hand rule.
Knowing the ampere force F of a wire with length d and current I in a magnetic field with magnetic induction B 1 The following formula is adopted for calculation:
F 1 =Id×B(1)
in the formula, I represents the current of the current-carrying conductor 1; d represents the length of the energized conductor 1; b represents magnetic induction intensity;
assuming that the internal magnetic field of the magnetic shield material 2 is weakened to ε B, where ε is a constant relating to the magnetic shield effect and satisfies ε < 1, the ampere force F to which the current-carrying conductor 1 covered with the magnetic shield material 2 is subjected 2 The following formula is adopted for calculation:
F 2 =εId×B (2)
the resultant force F applied to the electrified lead 1 is as follows:
F=(1-ε)Id×B (3)
the torque τ of the energized conductor 1 is calculated using the following equation:
τ=r×F=(1-ε)r×(I·d×B) (4)
where r denotes a vector between the open end of the flexible conduit 4 to the magnetic shield material 2;
according to the Euler-Bernoulli beam theory, the magnitude of the bending moment of deflection of the conduit | | τ L I is
Wherein E is the modulus of elasticity, I, of the flexible conduit 4 0 Is the area moment of inertia of the axial cross section of the flexible conduit 4, L represents the length of the flexible conduit 4; theta is the deflection angle, and thus the equilibrium equation for deflection of the flexible conduit 4 is
The deflection angle of the flexible conduit 4 can be obtained by the following equation
In the present invention, an external magnetic field can be generated by a system including a plurality of electromagnets. The magnetic field generated by an electromagnet is proportional to the current i supplied to the electromagnet, so that a system comprising n electromagnets generates a magnetic field B of
Wherein k is e For the ratio coefficient of the magnetic field generated by the electromagnet at that point to the energizing current, which is related to the electromagnet itself and to the point position, i e The current of the electromagnet is electrified.
As shown in fig. 3, the ampere force-based control method for the flexible catheter is to check the current position of the catheter by using a camera device, and obtain the required deflection angle of the catheter by combining with the expected movement route of the catheter. The control system calculates the magnetic field required by the steering and the current of the conducting wire in the conduit, and sends corresponding signals to the power supply to energize the electromagnet system and the conduit with corresponding currents, so that the conduit is deformed correspondingly. The catheter is finally moved to the target position by a number of iterations. The method specifically comprises the following steps:
s1: the flexible conduit 4, the exogenous camera 5, the magnetic field generating device 6, the controller 7 (generally a computer) and the power supply 8 form a control system, the camera 5 is connected with the controller 7 in the process of controlling the flexible conduit 4, and the power supply 8 is respectively connected with the opening end of the flexible conduit 4, the controller 7 and the magnetic field generating device 6;
s2: the camera 5 in the control system acquires the information of the position and the advancing line of the flexible conduit 4 and sends the information to the controller 7, and the controller 7 obtains the expected deflection angle theta of the flexible conduit 4 according to the acquired information;
s3: the correspondence between the desired deflection angle θ of the flexible conduit 4 and the magnetic induction of the magnetic field generating device 6 and the current of the energized conductor 1 is obtained using the following formula: wherein, when the magnetic induction intensity of the magnetic field generating device 6 conforming to the flexible conduit 4 is calculated, the current of the electrified conducting wire 1 is controlled to be unchanged; when the current of the electrified lead 1 which accords with the expected deflection angle theta of the flexible conduit 4 is calculated, the magnetic induction intensity of the magnetic field generating device 6 is controlled to be unchanged;
wherein E represents the elastic modulus of the flexible conduit 4; I.C. A 0 The area moment of inertia representing the axial section of the flexible conduit 4; b represents magnetic induction intensity; d represents the length of the energized conductor 1; i represents the current of the energized conductor 1; l represents the length of the flexible conduit 4; ε represents a constant relating to the effect of magnetic shielding; r represents a vector between the open end of the outer hose 3 and the magnetic shield material 2; in specific implementation, a plurality of magnetic shielding materials 2 are coated on the electrifying conducting wire 1 which is led from the open end of the outer hose 3 to the closed end of the outer hose 3, or a plurality of magnetic shielding materials 2 are coated on the electrifying conducting wire 1 which is led from the closed end of the outer hose 3 to the open end of the outer hose 3, so that the number of the magnetic shielding materials 2 is largeR in the equation is the sum of vectors between the respective magnetic shield materials 2 to the open end of the flexible conduit 4.
Under the condition that the current of the electrified conducting wire 1 is determined, a plurality of solutions may be obtained to meet the requirement when the required magnetic field B is calculated, and the optimal solution can be selected by using the following formula, namely, a group of solutions which enable the current variation of the electromagnet system to be minimum is selected:
in the formula i e Current required for electromagnet e, i e ' is the current energizing current of electromagnet e.
S4: according to the corresponding relation between the expected deflection angle theta of the flexible conduit 4, the magnetic induction intensity of the magnetic field generating device 6 and the current of the electrified lead 1, the controller 7 processes and obtains the magnetic induction intensity of the magnetic field generating device 6 or the current of the electrified lead 1 and sends an instruction to the power supply 8, the power supply 8 applies corresponding magnetic induction intensity to the magnetic field generating device 6 according to the obtained magnetic induction intensity instruction, at the moment, the current of the electrified lead 1 is kept unchanged, or the power supply 8 applies corresponding current to the flexible conduit 4 according to the obtained current instruction of the electrified lead 1, at the moment, the magnetic induction intensity of the magnetic field generating device 6 is kept unchanged;
then, under the action of a magnetic field or current, the ampere force borne by one section of the electrified lead 1 wrapped with the magnetic shielding material 2 in the outer-layer hose 3 is unequal to the ampere force borne by the other section of the electrified lead 1 not wrapped with the magnetic shielding material 2, so that the resultant force borne by the electrified lead 1 in the outer-layer hose 3 is not zero, namely the stress difference of the two sections of the electrified leads 1 is not zero, the flexible guide pipe 4 is subjected to an external force, the flexible guide pipe 4 deflects under the action of the external force, the deflection angle is recorded as an actual deflection angle alpha, and one deflection operation is completed;
s5: after the flexible conduit 4 finishes one deflection operation, the camera 5 detects whether the actual deflection angle alpha of the flexible conduit 4 is equal to the obtained expected deflection angle theta, and then the next step S6 is carried out;
s6: the following judgments were made: if the actual deflection angle alpha of the flexible conduit 4 detected by the camera 5 is equal to the expected deflection angle theta, the flexible conduit 4 continues to move along the advancing line;
if the actual deflection angle alpha of the flexible conduit 4 detected by the camera 5 is not equal to the expected deflection angle theta, taking the absolute value of the difference value between the actual deflection angle alpha of the flexible conduit 4 and the expected deflection angle theta as the expected deflection angle of the flexible conduit 4 for the next deflection operation, and then repeating the steps S3-S5 until the actual deflection angle of the flexible conduit 4 detected by the camera 5 is equal to the expected deflection angle; the current value of the current-carrying wire 1 or the magnetic induction value of the magnetic field generating device 6 for each deflecting operation is increased or decreased by a corresponding value based on the current value of the current-carrying wire 1 or the magnetic induction value of the magnetic field generating device 6 for the previous deflecting operation, and the current value of the current-carrying wire 1 or the magnetic induction value of the magnetic field generating device 6 for the first deflecting operation is the current value of the current-carrying wire 1 or the magnetic induction value of the magnetic field generating device 6 according to the expected deflection angle θ of the flexible catheter 4 in step S2 calculated by the calculation formula.
Therefore, when the flexible catheter manufactured by the method is used for controlling the posture of the catheter, the catheter can be placed in a constant magnetic field, and the deflection angle of the catheter is changed by changing the electrified current of the catheter, so that the posture of the catheter is controlled. In addition, the electrified current of the lead in the catheter can be kept unchanged, and the deflection angle of the catheter can be changed by changing the external magnetic field; the deflection angle of the catheter can also be changed by simultaneously changing the current of the wires in the catheter.
The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any minor modifications, equivalent replacements and improvements made on the above embodiment according to the technical essence of the invention should be included in the protection scope of the technical solution of the present invention.